These days, it's not uncommon for animals on various
continents to be related. Animals are
flown to be relocated in wildlife refuges, or even bred in-vitro in zoos. But what about woolly mammoths? Shouldn't their relations be restricted to
the same landmass, since they weren't exactly capable of travel by sea or
air? Apparently not, thanks to the help
of the Bering Strait land bridge.
It may help to learn a little history of the lineage of the
woolly mammoth. The animals are thought
to have descended from elephants that migrated north from Africa
– and needed to evolve to grow shaggy coats to keep warm. After the last ice age (about 10,000 years
ago), the species became extinct.
Woolly Mammoths – World Travelers?
Scientists from McMaster
University in Hamilton, Ontario
studied DNA samples from the teeth and jawbones of over 150 woolly mammoths, in
addition to examining data already on file.
The data concluded that over the course of hundreds of thousands of
years, the animals migrated back and forth between Alaska
and Eurasia four or five times.
Based on the radiocarbon dating and the DNA samples, it
appears that the first woolly mammoths migrated from Siberia to North America about 700,000 years ago. The relocated animals would then have evolved
separately, and therefore had slightly different DNA over the course of several-hundred
thousand more years.
The woolly mammoths with the slightly different genes made
their way back to Siberia about 300,000 years ago, and became extinct around 8,000
BC. The North American mammoths, on the other
hand, lived until about 10,000 years ago – around 6,000 BC.
Why the Siberian woolly mammoths died out before the
mammoths in North America, we're not
sure. It may be that climate, or even
humans, could have had an impact. Do you
think the cavemen were thinking about global warming as the ice melted and the
woolly mammoths died out?
Resources:
http://news.nationalgeographic.com/news/2008/09/080904-woolly-mammoth.html
http://en.wikipedia.org/wiki/Woolly_Mammoth
http://www.nytimes.com/2008/09/09/science/09obmamm.html?partner=rssnyt&emc=rss
http://dsc.discovery.com/news/2008/09/04/woolly-mammoth-arctic-02.html
http://www.current-biology.com/content/article/abstract?uid=PIIS0960982208009706
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